OpenEuphoria

Re: mathmatical question..

• Posted by Michael Bolin <michaeltom at GEOCITIES.COM> May 29, 1997
• 908 views

> Jiri's Reply has SOME merit mathmatically.
> However it is only 50% accurate.
>
> EXAMPLE
>
>   ________
>  |  _     |
>  | / |    |
>  |/  |    |
>  .   |____|
> /|\
>  |
> [point]
>
> If you take this polygon.
> You click to where his check comes exactly
> across the point. This would cause an odd count
> and still be inside the polygon.

No, in the case of ANY closed polygon, drawing a line from a point
and counting the number of intersections will ALWAYS work.

When counting the number of intersections mathematically, lines that
lie straight across another do not count as intersection points.

It's just a simple matter of topology. This system must ALWAYS work.

Michael Bolin